Replacement Heifer Management
Heifer development programs are very important aspects that affect ones ability to breed and calve. When selecting replacement heifers, it is important to select animals that are born early in the calving season and that reach puberty at a relatively early age. Puberty is defined as the state when female first expresses estrus and ovulated and must be achieved by under 15 months of age. Many things affect the age of puberty such as breed, nutrition, management after weaning, and maternal and paternal genetics.
There are specific management practices that can be implemented to promote reproductive success in heifers. Body weight at breeding time is recommended to be 62-65% relative to the mature body weight, there is evidence that lower body weights decrease the proportion of heifers in heat in all breeds of beef cattle. Proper management of the females is required from time of conception to rebreeding that heifer after her 1st calf in order to enhance that animals production ability, performance, and overall health. Nutrition plays a large role in puberty, breeding ability, and calving ease. Limit nutrition during the gestation phase can increase the risk of dystocia, produce weaker calves at birth, lower colostrum and milk production, and lower postpartum interval (PPI) and fertility. However, overfeeding can have negative effects on calving as fat deposits will develop in the pelvic opening which increases the risk of dystocia (difficult calving) as the calf does not have room to rotate properly. Fat deposits can also develop in the udder which will decrease colostrum and milk production. It is important to have heifers at a target weight approximately 85% of their mature body weight at calving.
Managing heifers needs to be done differently and often separately than older cows. Heifers should be bred earlier than cows. Younger animals cannot grow adequately on a maintenance diet used for mature cows when cattle are left grazing in the winter months due to the dormant, winter range being deficient in nutrients. Feeding them separately allows supplementation and does not force competition with larger, mature cows for feed access.